ML20248M045

Concludes That No Mods to Sys or Sys Operation Necessary at Facility for Completion of Action 9 for Paducah Gaseous Diffusion Plant & Portsmouth Gaseous Diffusion Plant

ML20248M045
Person / Time
Site:	Portsmouth Gaseous Diffusion Plant, 07007001
Issue date:	06/10/1998
From:	Pierson R NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To:	Toelle S UNITED STATES ENRICHMENT CORP. (USEC)
References
TAC-L32012, NUDOCS 9806120290
Download: ML20248M045 (4)

Text

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g 4 UNITED STATES NUCLEAR REGULATORY COMMISSION

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WASHINGTON O.C. 20066 4001 5

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June 10, 1998 7M/# b Mr. Steven Toelle, Manager -

Nuclear Regulatory Assurance and Policy U.S. Enrichment Corporation 2 Democracy Center.

6903 Rockledge Drive Bethesda, MD 20817

SUBJECT:

PADUCAH GASEOUS DIFFUSION PLANT AND PORTSMOUTH GASEOUS DIFFUSION PLANT, COMPLIANCE PLAN ISSUE 3, ACTION 9, ASME CODE INTERPRETATION AND ASSESSMENT RESULTS (TAC NO. L32012)

This letter is in response to your letter dated February 9,1998, in which U.S. Enrichment '

Corporation (USEC) addresses Compliance Plan issue 3, Action 9 for both Paducah Gaseous Diffusion Plant (PGDP) and Portsmouth Gaseous Diffusion Plant (PORTS). USEC concluded that no modifications to the system or system operation were necessary at either facility for -

completion of Action 9. The basis for this conclusion is that USEC has demonstrated adequate positive control of the externally steam heated parent / daughter transfer. The PORTS Action addresses the need for pressure relief for all UF, cylinder heating applications. The NRC staff has reviewed the ASME Code interpretation and subsequent analysis and determined that USEC's argument, that adequate positive control would obviate the need for a pressure relief device, is insufficient to satisfy the intent of Action 9.

BACKGROUND ,

in the current and proposed Safety Analysis Reports for both PGDP and PORTS, USEC commits to ASME Boiler and Pressure Vessel Code (the Code) Section Vill, with the exception that UF cylinders do not have pressure relief devices.

The Code, Section Vill, Division I, UG-125(a) states that all pressure vessels within the scope

. of this Division shall be provided with protective devices. The Code provides the following exception: in Subsection UG-125(g), the protective devices required in (a) above need not be

instailed directly on a pressure vessel when the source of pressure is external to the vessel and is under such positive control that the pressure in the vessel cannot exceed the maximum allowable working pressure at the operating temperature. While not directly applicable to Division I, Division ll, " Alternate Rules", Subsection AR-110, provides a list of types of protective 4 Ldevices that may be used: pressure relief valves, nonreclosing pressure relief devices, or flow

~ paths or vents, open directly or indirectly to the atmosphere.

I - EVALUATION l Even if the applicant can demonstrate suitable positive control as in Subsection UG-125(g) r g(

l ' referred to above, the applicant would still need to install some sort of protective device - not necessarily on the cylinder, itself - to satisfy the intent of the code. ,

9 O' '- ' S mac si m,.3,

_ _ _ - _ _ . _ - N.-__.-_-__. A

S. Toella, USEC 2 In following Action 9 (for PGDP), USEC obtained an interpretation from ASME in which ASME )

stated that the' requirements of UG-125(a) in Section Vill were invocable from the autoclave to the parent / daughter transfer. In the Engineering Notice provided as Enclosure 2 to the letter from USEC to the NRC dated December 31,1996, USEC stated that with additional ,

background information, ASME would reconsider the inquiry. However, resubmittal of the

- inquiry was never pursued, and USEC concluded no modifications would be necessary (i.e., the installation of a protechve device on the transfer line) to complete Action 9. After exchange of correspondence, USEC provided additional information in enclosures 1 and 2 of the letter dated February 9,1998. In this analysis, USEC contended that no modifications are necessary because USEC has demonstrated suitable positive control of the external heating source, which USEC interprets as satisfying the protective device provision. This is inconsistent with the Code provision, which still requires a protective device but allows it to be placed on the system rather then directly on the cylinder.

CONCLUSION 1

The NRC staff is not in position to establish an ASME Code interpretation that positive control of an external heating source would obviate the need for a protective device. The staff recommends that USEC comply with the Code, pursue en ASME Code interpretation from i ASME, or seek relief from the protective device provision for this externally heated transfer system from NRC. The basis for relief should be either that the current configuration provides an acceptable level of safety or that the necessary modification would cause hardship or unusual difficulty without a compensatory increase in safety. Provided in the enclosure is the type of discussion the NRC staff would need to review a relief request.

If you have any questions with regard to this letter, please contact Stephen Koenick at (301) 415-5228.  ;

1 Sincerely, OfiGi nal Si9d%

Robert C. Pierson, Chief Special Projects Branch Division of Fuel Cycle Safety and Safeguards, NMSS

Enclosure:

As stated Dockets 70-7001,70-7002 cc: Mr. Randall DeVault, DOE Mr. J. Morris Brown, PORTS DISTRIBUTION (Control No. 230S) .

Docket 70 7001. 70-7002 NRC File Center .PUBUC KO'Bnen, Rill NMSS Dir. Off. r# OGC CCox NMSS r# FCSS r# WSchwink. NMSS SPB r# . PHiland, Rill DHartland. Rlil WTroskonkl. FCoB i *See prewous concurrence OFC *SPB E -SPB E *SPB E *SPB E SPB, h gj1l NAME SKoenick:ij DHoadley YFaraz MHom hierson t DATE 5/21/98 5/26/98 6/8 /98 6/9/98 6/ /8/98 6/)0 /98 C = COVER E = COVER & ENCLOSURE - N = NO COPY g:\prv_let.dft OFFICIAL RECORD COPY -

w . .. ,. .. . . . .. .

. . _ 3

S. Toelb, USEC 2

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In flowing Action 9 (for PGDP), USEC obtained an interpretation from ASME in which ASME stat that the requirements of UG-125(a)in Section Vill were invocable from the autoclave to the pa nt/ daughter transfer. In the Engineering Notice provided as Enclosure 2 to the letter )

from US to the NRC dated December 31,1996, USEC stated that with additional l I

backgroun nformation, ASME would reconsider the inquiry. However, resubmittal of the inquiry was n er pursued, and USEC concluded no modifications would be necessary (i.e., the installation of a otective device on the transfer line) to complete Action 9. After exchange of I correspondence. EC provided additionalinformation in enclosures 1 and 2 of the letter dated February 9,1998. In is analysis, USEC contended that no modifications are necessary because they have dem strated suitable positive control of the external heating source, which l

they interpret as satisfying e protective device provision. This is inconsistent with the Code provision which still requires rotective device but enables it to be placed on the system rather then directly on the cylin CONCLUF!r)B The NRC staff is not in the position to esta 'sh an ASME Code interpretation of whether positive control would obviate the need for a tective device. The staff recommends that '

USEC pursue either an ASME Code interpretati or relief from the protective device provision for this externally heated transfer system. The bas for relief should be either that the current configuration provides arf acceptable level of safety o at the necessary modification would cause hardship or unusual difficulty without a compensa increase in safety. Provided in the enclosure is the type of discussions the NRC staff would n to review a relief request.

If you have any questions with regard to this letter, please conta an Martin at (301) 415-7254.

Sincerely, Robert C. Pierson, Chief Special Projects Branch Division of Fuel Cycle Safety and Safeguards, NMSS

Enclosure:

As stated Dockets 70-7001,70-7002 cc: Mr. Randall DeVault, DOE Mr. J. Morris Brown, PORTS DISTRIBUTION / No. 230S)

Docket 70-7002 RC F61e Center PUBuc Ko'Bnen. Rill NMSS Dir. off. r/r oGC CCox NMSS r/f FCSS r/f WSchwink. NMSS SPB r/f PHiland. Rill DHartland. Rill WTroskoski. FCoB A %M015L 3 POR OFC SPB [$PB SPB SPB b FCSS NMSS NARIE SKoen#ck 1) NMpadlyy YFara M DMartin RP,erson DATE #

6/t\ /98 8 6 // 8 /98 h/ 1198 5/ /98 5/ /98 / /98

• ( c. COVER E = COVER & ENCLOSURE N = NO COPY OFFICIAL RECORD COPY g:\prv, Jet.dft

1 Type of Information NRC Requires to Review a Relief Request

)j U.S. Enrichment Corporation Paducah and Portsmouth Gaseous Diffusion Plants Dockets 70-7001 and 70-7002 Ba- s for relief from the pressure ASME Code requirement for a relief device for the UF.

transfer system should be either:

a. The configuration as it currently exists provides an suceptable level of safety, or

b. Compliance with the Code requirement would provide hardship or unusual difficulty without a compensating increase in safety.

Either approach could be demonstrated by utilizing the various identified accident scenarios in the Hazard Analysis and showing that the current configuration is acceptable or compliance would lead to undue hardship without a compensatory increase in safety.

Relevant Accident Analysis Results in Section 4.3.2 contained in both proposed SARUPs:

4.3.2.2.2 Autoclave Steam Control Valve Fails Open (Pressure increase);

4.3.2.2.6 Heating of a Cylinder with Excessive UF,(Pressure increase);

4.3.2.2.7 Heating of a Cylinder with Excessive Noncondensables (Pressure Increase); and 4.3.2.2.14 Cylinder Failure Inside Autoclave (Primary System Integrity).

These individual writeups provide description of the relevant accident scenarios (including initial conditions, bounding cases and necessary controls), consequence analysis, and summary of SSCs and TSRs. These writeups should be supported with the appropriate calculations, relevant margins, and additional assurance of the initial conditions and relied-upon safety controls.

In addition to these accidents scenarios, the differences in the PORTS and PGDP configurations should be noted: specifically none of PORT 3 transfer and sample systems contain pressure relief devices, but they do have a UF. cylinder high temperature steam cutoff systern. PGDP L does have pressure relief devices on all of their systems with the exception of the C-360 transfer and sample station transfer mode.

ENCLOSURE i